Our proposed research is aimed at providing a systematic approach and an eventual mechanistic understanding of the kinetic factors associated with cholesterol gallstone dissolution in bile from the physical chemical viewpoint. It involves the experimental and theoretical evaluation of the influences of the principal constituents of human bile by conducting dissolution rate studies of cholesterol gallstones and cholesterol monohydrate "model gallstones" in chemically defined media and comparing these results with those obtained with human gallbladder bile. Emphasis is being directed toward the assessment of the importance and the understanding of the interfacial resistance factor which rate limits stone dissolution in vitro and, probably, in $ many in vivo situations corresponding to certain bile compositions. Results of current studies will be used to examine in vivo dissolution data from patients being treated for stones with orally administered chenodeoxycholic acid. Also the present results are being used to provide an explanation of why certain formulations for T-tube infusion treatment of retained common duct stones appear to be more clinically effective than others. Efforts are being put into seeking out and studying conditions, procedures, and chemical agents that may, from a kinetic viewpoint, significantly accelerate cholesterol gallstone dissolution. An animal model will be studied for testing in in vitro findings with regard to effectiveness.